Many of the victims in Herat province are women and children. Separately, a suicide bomber attacks a U.S. base in Paktia, killing two Afghan security guards.

Reporting from Islamabad, Pakistan, and Kabul, — A roadside bomb killed 22 people, many of them women and children, crammed into a minivan in western Afghanistan on Thursday, a grim reminder of the toll that the 10-year war against Taliban insurgents takes on civilians.

The blast was one of two that struck civilians in the Owbeh district of the western province of Herat on Thursday morning. A separate roadside bomb killed an Afghan woman and injured seven people in a small Mazda truck, said Mohayuddin Noory, a spokesman for the Herat governor's office.

In a third attack Thursday morning, a suicide bomber rammed a truck filled with explosives into the entrance of a heavily guarded U.S. base for military and civilian operations in Gardez, the capital of the eastern province of Paktia, killing two Afghan security guards. Nine Afghan civilian laborers were injured in the attack, said Rohullah Samoon, a spokesman for the Paktia governor's office.

The base is one of more than 20 provincial reconstruction team centers scattered throughout Afghanistan that provide Afghan government officials with guidance on local development and rebuilding projects. The base at Gardez was the program's first.

The Taliban claimed responsibility for the attack in Gardez. Zabiullah Mujahid, a spokesman for the militant group, said the assault killed 27 soldiers and wounded 34, though insurgents usually exaggerate the number of dead and wounded in operations they carry out.

Noory said the minivan was on its way to a bazaar when the roadside bomb detonated, killing everyone inside. Traffic to the bazaar had increased recently as people had begun shopping in preparation for Eid holidays at the end of the Muslim holy month of Ramadan, Noory said.

President Hamid Karzai issued a statement condemning the attacks in Herat, saying the militants "should understand that, by committing crimes such as this in the month of Ramadan, they will win nothing but hatred from the poor families of this country."

Afghan civilians have borne the brunt in the war between the Taliban insurgency and Western and Afghan troops, with most of the deaths caused by the militants.

In the first half of the year, 1,462 Afghan civilians died, a 15% increase from the same period in 2010, according to United Nations statistics, with four-fifths of the deaths caused by the Taliban.

One of the primary factors was the militants' heavier reliance on improvised explosive devices, or homemade bombs, U.N. officials said. The bombs, often buried in dirt roads, are equipped with sensitive pressure plates that can be triggered by the weight of a passerby.